In recent years, the Peer-to-Peer (abbreviated as P2P) rapidly becomes one of hot topics in the computer industry. The P2P is a distributed network. Participants in the P2P network share a part of their hardware resources, including: processing capability, storage capability and network connection capability of participants. The shared resources require the network to provide services and content that can be accessed directly by other peers via no intermediate entities. The participants in the network are not only providers (Servers) of the resources (services and content) but also obtainers (Clients) of the resources (services and content).
The P2P technique draws great attention at present. The utilization of software such as BT, eMule and PPLive makes people foresee the foreground of the P2P technique in telecommunications field. The soul of the P2P network lies in its loose management mode. This mode gives more freedom to users but it is difficult to manage. For example, because there are a lot of users in the P2P network, a lot of search results may be obtained if a user performs a search. The majority of the search information may be junk information except a minority of useful information. Because it is difficult for the P2P network to order the search results due to lack of concentrated management, it is inevitable for the users to be surrounded by the junk information. Also, due to the randomness of joining, usage and quit of the P2P peers, the P2P network becomes unstable and cannot therefore provide quality of service for the users, which influences the commercialization of this technique in telecommunications field. In addition, it is well-known that users in the P2P network may occupy a large amount of network bandwidths, which influences bandwidth usage of non-P2P network users in the same network. For example, at present users connected with the P2P network occupy a large amount of network bandwidths, which influences bandwidth usage of other users in the telecommunications network and results in that the operators such as China Telecom have to disable the port of the users connected with the P2P network.
At present, popular P2P software BitTorrent (abbreviated as BT) has had certain management capabilities. The BT system needs a Web server, which is also called Tracker. The Tracker is responsible for maintaining a resource list and updating resource occupied by the respective peers periodically. All peers of the P2P network can obtain resource distribution as required only by query in the Tracker. When a connection is established between a peer and the Tracker, the Tracker collects information from all downloaders and helps to match them. Because the Tracker provides very limited user list information, a user cannot determine which peers in the list can actually provide a service. Therefore, the user needs to try to establish connections to all objects in the list, and always maintains the connections so as to wait for a “possible” service provided by an opposite party. In other words, each user should establish around a hundred of external connections, however, usable links are few, which not only occupies the user's resource but also wastes network bandwidth. Furthermore, the Tracker, connected with the respective peers, via a fixed port, is subject to external attacks.